Australasian ACPGBI risk prediction model for 30-day mortality after colorectal cancer surgery.

BACKGROUND: Postoperative mortality after colorectal cancer surgery varies across hospitals and countries. The aim of this study was to test the Association of Coloproctologists of Great Britain and Ireland (ACPGBI) models as predictors of 30-day mortality in an Australian cohort. METHODS: Data from patients who underwent surgery in six hospitals between 1996 and 2015 (CRC data set) were reviewed to test ACPGBI models, and patients from 79 hospitals in the Bi-National Colorectal Cancer Audit between 2007 and 2016 (BCCA data set) were analysed to validate model performance. Recalibrated models based on ACPGBI risk models were developed, tested and validated on a data set of Australasian patients. RESULTS: Of 18 752 patients observed during the study, 6727 (CRC data set) and 3814 (BCCA data set) were analysed. The 30-day mortality rate was 1·1 and 3·5 per cent in the CRC and BCCA data sets respectively. Both the original and revised ACPGBI models overestimated 30-day mortality for the CRC data set (observed to expected (O/E) ratio 0·17 and 0·21 respectively). Their ability to correctly predict mortality risk was poor (P < 0·001, Hosmer-Lemeshow test); however, the area under the curve for both models was 0·88 (95 per cent c.i. 0·85 to 0·92) showing good discriminatory power to classify 30-day mortality. The recalibrated original model performed well for calibration and discrimination, whereas the recalibrated revised model performed well for discrimination but not for calibration. Risk prediction was good for both recalibrated models. On external validation using the BCCA data set, the recalibrated models underestimated mortality risk (O/E ratio 3·06 and 2·98 respectively), whereas both original and revised ACPGBI models overestimated the risk (O/E ratio 0·48 and 0·69). All models showed similar good discrimination. CONCLUSION: The original and revised ACPGBI models overpredicted risk of 30-day mortality. The new Australasian calibrated ACPGBI model needs to be tested further in clinical practice.

ANTECEDENTES: La mortalidad postoperatoria tras la cirugía del cancer colorrectal (colorectal cáncer, CRC) varía entre hospitales y países. El objetivo de este estudio era evaluar los modelos de la Asociación de Coloproctólogos de Gran Bretaña e Irlanda (Association of Coloproctologists of Great Britain and Ireland, ACPGBI) como predictores de mortalidad a los 30 días en una cohorte de pacientes de Australia. MÉTODOS: Se revisaron los datos de pacientes sometidos a cirugía en seis hospitales entre 1996-2015 (datos CRC) para evaluar los modelos ACPGBI, mientras que los datos recogidos en 79 hospitales en la auditoría bi-nacional de cáncer colorrectal (Bi-National Colorectal Cancer Audit) entre 2007-2016 (datos BCCA) se analizaron para validar el comportamiento del modelo. Se desarrollaron modelos recalibrados basados en los modelos de riesgo ACPGBI que fueron aplicados y validados en un conjunto de datos multi-institucionales de pacientes australianos. La mortalidad observada y estimada (tasa 0/E) a 30 días se calculó en los modelos ACPGBI original y revisados usando el test de Hosmer-Lemeshow y los análisis de la curva de las características operador-receptor (ROC) para evaluar la calibración y discriminación de los modelos. RESULTADOS: De un total de 18,752 pacientes observados durante el periodo de estudio, se analizaron 6.727 (datos CRC) y 3.814 (datos BCCA). La mortalidad en los pacientes del grupo de datos CRC fue del 1,1% y en los del grupo de datos BCCA del 3,5%. Para el grupo de datos CRC, los modelos ACPGBI sobreestimaron significativamente la mortalidad a los 30 días, tanto en el modelo original como en el modelo revisado (O/E 0,17 y 0,21). La capacidad de los modelos para predecir correctamente el riesgo de mortalidad también fue limitada (test de Hosmer-Lemeshow 23,1 y 22.9); sin embargo, el área bajo la curva ROC de ambos modelos fue de 0,88 (i.c. del 95% 0,85-0,92) con una buena capacidad discriminatoria para clasificar a los pacientes que fallecían durante los primeros 30 días tras la cirugía. El modelo original ACPGBI recalibrado presentó un buen comportamiento para la predicción de riesgo (tasa O/E 1,06), pero no fue así en el caso del modelo revisado ACPGBI recalibrado (tasa O/E 0,99). En la validación externa con los datos BCCA, los modelos recalibrados subestimaron el riesgo de mortalidad a los 30 días (tasa O/E 3,06 y 2,98), mientras que los modelos ACPGBI original y revisado sobreestimaron el riesgo (tasa O/E 0,48 y 0,69, respectivamente). Todos los modelos mostraron una buena discriminación en las curvas ROC. CONCLUSIÓN: Los modelos ACPGBI original y revisado sobreestimaron el riesgo de mortalidad a los 30 días. Se desarrolló un nuevo modelo, denominado modelo ACPGBI calibrado australiano o modelo ACACPGBI, cuya utilidad en la práctica clínica debe ser evaluada.

Role of lymph node yield and lymph node ratio in predicting outcomes in non-metastatic colorectal cancer.

Background: Lymph node yield (LNY) of 12 or more in resection of colorectal cancer is recommended in current international guidelines. Although a low LNY (less than 12) is associated with poorer outcome in some studies, its prognostic value is unclear in patients with early-stage colorectal or rectal cancer with a complete pathological response following neoadjuvant therapy. Lymph node ratio (LNR), which reflects the proportion of positive to total nodes obtained, may be more accurate in predicting outcome in stage III colorectal cancer. This study aimed to identify factors correlating with LNY and evaluate the prognostic role of LNY and LNR in colorectal cancer. Methods: An observational study was performed on patients with colorectal cancer treated at three hospitals in Melbourne, Australia, from January 2010 to March 2016. Association of LNY and LNR with clinical variables was analysed using linear regression. Disease-free (DFS) and overall (OS) survival were investigated with Cox regression and Kaplan-Meier survival analyses. Results: Some 1585 resections were analysed. Median follow-up was 27·1 (range 0·1-71) months. Median LNY was 16 (range 0-86), and was lower for rectal cancers, decreased with increasing age, and increased with increasing stage. High LNY (12 or more) was associated with better DFS in colorectal cancer. Subgroup analysis indicated that low LNY was associated with poorer DFS and OS in stage III colonic cancer, but had no effect on DFS and OS in rectal cancer (stages I-III). Higher LNR was predictive of poorer DFS and OS. Conclusion: Low LNY (less than 12) was predictive of poor DFS in stage III colonic cancer, but was not a factor for stage I or II colonic disease or any rectal cancer. LNR was a predictive factor in DFS and OS in stage III colonic cancer, but influenced DFS only in rectal cancer.

Surgical outcome after standard abdominoperineal resection: A 15-year cohort study from a single cancer centre.

BACKGROUND: Abdominoperineal resection (APR) is associated with a poorer oncological outcome than anterior resection. This may be due to higher rates of intra-operative perforation and circumferential resection margin involvement. The aim of this study was to audit our short and long-term results of abdominoperineal resection performed using conventional techniques and to compare this with other published series. MATERIALS AND METHODS: A retrospective review of all patients who had standard APR between January 2000 and December 2016 in a single institution, Cabrini Hospital, Melbourne, Australia. A total of 163 cases performed by nine different colorectal surgeons for primary rectal adenocarcinoma were identified, with their clinicopathological data analysed. RESULTS: Using standard APR, only six patients (3.7%) were found to have a positive circumferential resection margin (CRM). There were two cases of intra-operative perforation (1.2%). Local recurrence rate was 5.6% of patients, with distant recurrence found in 24.9%. Disease-free survival at five years was 73.1%. Five-year overall survival was 66.7%, 67.9% of all deaths were cancer-related. CONCLUSION: Short and long-term outcomes after standard APR in this study were comparable to previous published studies. The CRM rate of 3.7% compares favourably to published positive CRM rates for standard APR which ranged from 6 to 18%. Standard APR remains a viable technique for the treatment of rectal cancer. Patient selection and adequate training remain important factors.

The effect of increasing body mass index on laparoscopic surgery for colon and rectal cancer.

AIM: Obesity is common in Western countries and its prevalence is increasing. Colorectal cancer is common, and surgery for colorectal cancer is technically more challenging in obese patients. Laparoscopic surgery for colon cancer has been shown to be oncologically equivalent, with improved short- term outcomes. Laparoscopic surgery for rectal cancer has proven technically challenging, and recent results have raised concerns about oncological equivalence. Our aim was to evaluate the effect of body mass index (BMI) on the clinical and oncological outcomes of surgery for colorectal cancer, including the rate at which laparoscopic surgery is attempted and the rate at which laparoscopic surgery is converted to open surgery. METHOD: A retrospective analysis of prospectively collected data from two tertiary institutions was performed. Data were obtained from the Cabrini Monash University colorectal neoplasia database for patients having surgical resection for colon and rectal cancers between 1 January 2010 and 30 June 2015. Surgical and medical complications, tumour recurrence and overall survival and laparoscopic surgery and conversion rates were investigated. RESULTS: This large case series of 1464 patients undergoing elective surgery for colorectal cancer has demonstrated that an elevated BMI is associated with a lower likelihood of attempting laparoscopic surgery and a higher conversion rate to open surgery when laparoscopy is attempted. Conversion was 1.9 times more likely in obese patients with colon cancer and 4.1 times more likely in obese patients with rectal cancer. The critical BMI for colon cancer patients was > 35 kg/m2 , and for rectal cancer patients > 30 kg/m2 . Obesity is also associated with increased rates of surgical complications, including anastomotic leakage and wound complications. Pathological parameters, tumour recurrence and survival were not affected by elevated BMI. CONCLUSION: In the surgical management of colorectal cancer, obesity is associated with a lower likelihood of laparoscopic surgery being attempted, a higher likelihood of conversion to open surgery when laparoscopic surgery is attempted, and a higher rate of surgical complications.

The first 1000 patients on an internet-based colorectal neoplasia database across private and public medicine in Australia: development of a binational model for the Colorectal Surgical Society of Australia and New Zealand.

BACKGROUND: Collection of multi-institutional data pertaining to the treatment of bowel cancer has been hindered by poor clinician compliance with data entry and the lack of incentive to participate. OBJECTIVE: This study aimed to establish if a novel browser-based model of data collection results in complete data capture. DESIGN: A Web-based data collection interface was custom written, offering automated reporting modules for clinical outcome to participants and an automated reporting system for outstanding data fields, and summary reporting of surgical quality outcomes. The software was combined with a clinical feedback system incorporating fortnightly data review meetings, at the time of clinical multidisciplinary meetings. PATIENTS AND SETTING: Selected were 932 consecutive patients with opt-out consent from 3 hospital sites, including public and private medicine. MAIN OUTCOME MEASURES: The primary outcomes measured were the analysis of data completeness and accuracy and ensuring that the highest-quality data were used for clinical audit of the surgical practices of Australian colorectal surgeons for the purpose of quality assurance. RESULTS: A total of 932 men and women, 22 to 94 years of age, treated for colorectal neoplasia were evaluated. We obtained 100% completion (>27,000 data points) of perioperative data registered by 8 specialist colorectal surgeons and a full-time database manager. CONCLUSIONS: Data completeness and validity are essential for clinical databases to serve the purpose of quality assurance, benchmarking, and research. The results confirm the safety and efficacy of colorectal cancer surgery in both the public and private sector in Australia. The combination of a simple multiuser interface, defined data points, automated result-reporting modules, and data-deficiency reminder module resulted in 100% data compliance in nearly 1000 clinical episodes. The unprecedented success of this model has lead to the Colorectal Surgical Society of Australia and New Zealand adopting this model for data collection for Australia and New Zealand as the binational database.

Ascites induces modulation of alpha6beta1 integrin and urokinase plasminogen activator receptor expression and associated functions in ovarian carcinoma.

Interactions between cancer cells and the surrounding medium are not fully understood. In this study, we demonstrate that ascites induces selective changes in the expression of integrins and urokinase plasminogen activator/urokinase plasminogen activator receptor (uPA/uPAR) in ovarian cancer cells. We hypothesise that this change of integrin and uPA/uPAR expression triggers signalling pathways responsible for modulating phenotype-dependent functional changes in ovarian cancer cells. Human ovarian surface epithelial (HOSE) cell lines and epithelial ovarian cancer cell lines were treated with ascites for 48 h. Ascites induced upregulation of alpha6 integrin, without any change in the expression of alphav, beta1 and beta4 integrin subunits. Out of the four ovarian cancer cell lines studied, ascites induced enhancement in the expression of uPA/uPAR in the more invasive OVCA 433 and HEY cell lines without any change in the noninvasive OVHS1 and moderately invasive PEO.36 cell lines. On the other hand, no change in the expression of alpha6 integrin or uPAR, in response to ascites, was observed in HOSE cells. In response to ascites, enhancement in proliferation and in adhesion was observed in all four ovarian cancer cell lines studied. In contrast, no significant increase in proliferation or adhesion by ascites was observed in HOSE cells. Ascites-induced expression of uPA/uPAR correlated with the increased invasiveness of HEY and OVCA 433 cell lines but was not seen in OVHS1, PEO.36 and HOSE cell lines. Upregulation of alpha6 integrin and uPA/uPAR correlated with the activation of Ras and downstream Erk pathways. Ascites-induced activation of Ras and downstream Erk can be inhibited by using inhibitory antibodies against alpha6 and beta1 integrin and uPAR, consistent with the inhibition of proliferation, adhesion and invasive functions of ovarian cancer cell lines. Based on these findings, we conclude that ascites can induce selective upregulation of integrin and uPA/uPAR in ovarian cancer cells and these changes may modulate the functions of ovarian carcinomas.

Enhanced expression of peroxisome proliferator-activated receptor gamma in epithelial ovarian carcinoma.

The peroxisome proliferator-activated receptors (PPARs) belong to a subclass of nuclear hormone receptor that executes important cellular transcriptional functions. Previous studies have demonstrated the expression of PPARgamma in several tumours including colon, breast, bladder, prostate, lung and stomach. This study demonstrates the relative expression of PPARgamma in normal ovaries and different pathological grades of ovarian tumours of serous, mucinous, endometrioid, clear cell and mixed subtypes. A total of 56 ovarian specimens including 10 normal, eight benign, 10 borderline, seven grade 1, nine grade 2 and 12 grade 3 were analysed using immunohistochemistry. Immunoreactive PPARgamma was not expressed in normal ovaries. Out of eight benign and 10 borderline tumours, only one tumour in each group showed weak cytoplasmic PPARgamma expression. In contrast, 26 out of 28 carcinomas studied were positive for PPARgamma expression with staining confined to cytoplasmic and nuclear regions. An altered staining pattern of PPARgamma was observed in high-grade ovarian tumours with PPARgamma being mostly localized in the nuclei with little cytoplasmic immunoreactivity. On the other hand, predominant cytoplasmic staining was observed in lower-grade tumours. Significantly increased PPARgamma immunoreactivity was observed in malignant ovarian tumours (grade 1, 2 and 3) compared to benign and borderline tumours (chi2 = 48.80, P < 0.001). Western blot analyses showed significant elevation in the expression of immunoreactive PPARgamma in grade 3 ovarian tumours compared with that of normal ovaries and benign ovarian tumours (P < 0.01). These findings suggest an involvement of PPARgamma in the onset and development of ovarian carcinoma and provide an insight into the regulation of this molecule in the progression of the disease.

Proteomic-based identification of haptoglobin-1 precursor as a novel circulating biomarker of ovarian cancer.

Screening for specific biomarkers of early-stage detection of ovarian cancer is a major health priority due to the asymptomatic nature and poor survival characteristic of the disease. We utilised two-dimensional gel electrophoresis (2DE) to identify differentially expressed proteins in the serum of ovarian cancer patients that may be useful as biomarkers of this disease. In this study, 38 ovarian cancer patients at different pathological grades (grade 1 (n=6), grade 2 (n=8) and grade 3 (n=24)) were compared to a control group of eight healthy women. Serum samples were treated with a mixture of Affigel-Blue and protein A (5 : 1) for 1 h to remove high abundance protein (e.g. immunoglobulin and albumin) and were displayed using 11 cm, pH 4-7 isoelectric focusing strips for the first dimension and 10% acrylamide gel electrophoresis for the second dimension. Protein spots were visualised by SYPRO-Ruby staining, imaged by FX-imager and compared and analysed by PDQuest software. A total of 24 serum proteins were differentially expressed in grade 1 (P<0.05), 31 in grade 2 (P<0.05) and 25 in grade 3 (P<0.05) ovarian cancer patients. Six of the protein spots that were significantly upregulated in all groups of ovarian cancer patients were identified by nano-electrospray quadrupole quadrupole time-of-flight mass spectrometry (n-ESIQ(q)TOFMS) and matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOFMS) as isoforms of haptoglobin-1 precursor (HAP1), a liver glycoprotein present in human serum. Further identification of the spots at different pathological grades was confirmed by Western blotting using monoclonal antibody against a haptoglobin epitope contained within HAP1. Immunohistochemical localisation of HAP1-like activity was present in malignant ovarian epithelium and stroma but strong immunostaining was present in blood vessels, areas with myxomatous stroma and vascular spaces. No tissue localisation of HAP1-like immunoreactivity was observed in normal ovarian surface epithelium. These data highlight the need to assess circulating concentration of HAP1 in the serum of ovarian cancer patients and evaluate its potential as a biomarker in the early diagnosis of ovarian cancer.

Downregulation of urokinase plasminogen activator receptor expression inhibits Erk signalling with concomitant suppression of invasiveness due to loss of uPAR-beta1 integrin complex in colon cancer cells.

Cancer invasion is regulated by cell surface proteinases and adhesion molecules. Interaction between specific cell surface molecules such as urokinase plasminogen activator receptor (uPAR) and integrins is crucial for tumour invasion and metastasis. In this study, we examined whether uPAR and beta1 integrin form a functional complex to mediate signalling required for tumour invasion. We assessed the expression of uPAR/beta1 integrin complex, Erk signalling pathway, adhesion, uPA and matrix metalloproteinase (MMP) expression, migration/invasion and matrix degradation in a colon cancer cell line in which uPAR expression was modified. Antisense inhibition of the cell surface expression of uPAR by 50% in human colon carcinoma HCT116 cells (A/S) suppressed Erk-MAP kinase activity by two-fold. Urokinase plasminogen activator receptor antisense treatment of HCT116 cells was associated with a 1.3-fold inhibition of adhesion, approximately four-fold suppression of HMW-uPA secretion and inhibition of pro-MMP-9 secretion. At a functional level, uPAR antisense resulted in a four-fold decline in migration/invasion and abatement of plasmin-mediated matrix degradation. In empty vector-transfected cells (mock), uPA strongly elevated basal Erk activation. In contrast, in A/S cells, uPA induction of Erk activation was not observed. Urokinase plasminogen activator receptor associated with beta1 integrin in mock-transfected cells. Disruption of uPAR-beta1 integrin complex in mock-transfected cells with a specific peptide (P25) inhibited uPA-mediated Erk-MAP kinase pathway and inhibited migration/invasion and plasmin-dependent matrix degradation through suppression of pro-MMP-9/MMP-2 expression. This novel paradigm of uPAR-integrin signalling may afford opportunities for alternative therapeutic strategies for the treatment of cancer.

Glucose-induced release of tumour necrosis factor-alpha from human placental and adipose tissues in gestational diabetes mellitus.

AIMS: The cytokine tumour necrosis factor-alpha (TNF-alpha) has been implicated in the pathogenesis of insulin resistance in Type 2 diabetes mellitus, but limited data are available in relation to gestational diabetes mellitus (GDM), a disease in which similar biochemical abnormalities exist. We investigated the effect of exogenous glucose on the release of TNF-alpha from placental and adipose (omental and subcutaneous) tissue obtained from normal pregnant women, and women with GDM. METHODS: Human tissue explants were incubated for up to 24 h and TNF-alpha concentration in the incubation medium quantified by ELISA. The effect of normal (5 mmol/l) and high (15 and 25 mmol/l) glucose concentrations on the release of TNF-alpha was assessed. RESULTS: In placental and subcutaneous adipose tissues obtained from women with GDM (n = 6), TNF-alpha release was significantly greater under conditions of high glucose compared with normal glucose (placenta, 25 mmol/l 5915.7 +/- 2579.6 and 15 mmol/l 4547.1 +/- 2039.1 vs. 5 mmol/l 1897.1 +/- 545.5; subcutaneous adipose tissue, 25 mmol/l 423.5 +/- 207.0 and 15 mmol/l 278.5 +/- 138.7 vs. 5 mmol/l 65.3 +/- 28.5 pg/mg protein; P < 0.05). In contrast, there was no stimulatory effect of high glucose on TNF-alpha release by tissues obtained from normal pregnant women (n = 6) (placenta, 25 mmol/l 1542.1 +/- 486.2 and 15 mmol/l 4263.3 +/- 2737.7 vs. 5 mmol/l 5422.4 +/- 1599.0; subcutaneous adipose tissue, 25 mmol/l 189.8 +/- 120.4 and 15 mmol/l 124.5 +/- 32.3 vs. 5 mmol/l 217.9 +/- 103.5 pg/mg protein). CONCLUSIONS: These observations suggest that tissues from patients with GDM release greater amounts of TNF-alpha in response to high glucose. As TNF-alpha has been previously implicated in the regulation of glucose and lipid metabolism, and of insulin resistance, these data are consistent with the hypothesis that TNF-alpha may be involved in the pathogenesis and/or progression of GDM.

Analysis of chorionic gonadotrophin secreted by cultured human blastocysts.

Embryos produced in an in-vitro fertilization (IVF) programme, but which were unsuitable for transfer to patients because they originated from one (1PN) or three pronuclear (3PN) oocytes or because they originated from two pronuclear (2PN) oocytes but cleaved normally, were maintained in tissue culture. The embryos that progressed to blastocytes were cultured to day 14 of development in order to study their daily output of human chorionic gonadotrophin (HCG). Blastocysts that released large amounts of immunoreactive HCG, which continued to increase daily during the study period, provided the culture supernatants used in the present studies. The heterogeneity of HCG released by blastocyst tissues on days 11 and 14 of development was studied by a chromatofocusing method which separates the isoforms of the gonadotrophin based on differences in their isoelectric points. It was found that the secreted HCG was composed of several molecular forms and that this heterogeneity changed from day 11 to 14 of development. The early blastocyst tissues produced more acidic HCG isoforms than the more advanced embryonic tissues. Differences in the apparent ploidy of the blastocyst tissues studied did not affect significantly the distribution of the HCG isoforms secreted either on day 11 or day 14 of development. These results suggest that the bioactivity of the HCG secreted by blastocytes may change with time and with differentiation of the trophectoderm. In addition, the results suggest that the ploidy of early blastocytes does not influence the nature of the HCG secreted.

Chorionic gonadotrophin secretion by human blastocysts.

Abnormal embryos that arose in our in-vitro fertilization programme were cultured in serum-free minimum essential medium (MEM), and those that developed into blastocysts were cultured up to day 14 after fertilization to study the influence of various supplements on chorionic gonadotrophin (CG) secretion. Human cord serum, at a concentration of 1%, was found to be one of the most effective stimulants for initiating and maintaining CG production. A mixture of insulin+transferrin+selenium (ITS) stimulated CG secretion in serum-free MEM, although the output of hormone began to decline after approximately 3 days. Platelet-derived growth factor (PDGF) produced a similar response to ITS. Stimulation of blastocyst CG secretion in the absence of serum could also be induced with 8-bromo-cAMP. All stimulants were able to evoke CG secretion in day 7-8 blastocysts. These studies have shown that multiple factors were capable of inducing CG production by early blastocysts. On the basis of these and other studies it was postulated that receptors for insulin, transferrin and PDGF were expressed in preimplantation blastocysts.

Embryonic development and blastocyst implantation following in vitro fertilization and embryo transfer.

A sensitive and specific radioimmunoassay was used to measure human chorionic gonadotropin (hCG) excretion in serial overnight urine samples in women having embryo transfer, in an in vitro fertilization program. Elevated hCG excretion suggestive of blastocyst implantation was detected in 17 of 121 women studied. When the results were corrected for interference by luteinizing hormone and other immunoreactive substances, implantation was detectable 8 to 9 days after fertilization in 20% of conceptual cycles, in 80% by days 12 to 13, in 93% by days 14 to 15, and in 100% by days 16 to 17. From a life table of human embryo development in culture, it was estimated that 37% of four-cell and 43% of eight-cell embryos reached the blastocyst stage. On the basis of these estimates and the elevated hCG from implanting blastocysts, it was concluded that 60% to 65% of uterine blastocysts either failed to implant or failed to produce measurable hCG.

PIP: A sensitive and specific radioimmunoassay was used to measure human chorionic gonadotropin (hCG) excretion in serial overnight urine samples in women having embryo transfer, in an in vitro fertilization program. Elevated hCG excretion suggestive of blastocyst implantation was detected in 17 of 21 women studied. When results were corrected for interference by luteinizing hormone and other immunoreactive substances, implantation was detectable 8-9 days after fertilization in 20% of conceptual cycles, in 80% by days 12-13, in 93% by days 14-15, and in 100% by days 16-17. From a life table of human embryo development in culture, it was estimated that 37% of 4-cell and 43% of 8-cell embryos reached the blastocyst stage. On the basis of these estimates and the elevated hCG from implanting blastocysts, it was concluded that 60-65% of uterine blastocysts either failed to implant or failed to produce measurable hCG.